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Proceedings Paper

Non-destructive detection of lead glass alteration by reflectance spectroscopy
Author(s): Mady Elias; Cécile Charbonneau; Jean Marc Frigerio
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Paper Abstract

A non-destructive technique giving an early diagnosis of glass degradation is presented here. It allows to implement a new sol-gel method that stops further deterioration of the glass and avoid the classical removing of crusts. Reflectance spectroscopy in the visible range is used with a portable fiber-optics spectrophotometer in a back-scattered configuration and underlines very fine levels of glass alteration. Quantitative validations on reference samples are first presented. The reference glasses have varying amounts of lead and have been damaged using a defined and controlled degradation process. The deterioration begins by an increase in the roughness of the upper surface, quantified by an upward vertical translation of the reflectance spectra. For glasses containing an important amount of lead, it is followed by a decrease in this roughness and the apparition of periodic oscillations of spectrum, due to interferences inside a transparent layer created by the loss of lead. The analysis of these oscillations leads to the quantification of the thickness of the altered layer and to its evolution with the degradation. These results have been validated by RBS analysis. The same measurements have been implemented on archeological samples that have been damaged by naturally occurring reactions while being buried in soil. Comparisons of features and oscillations of the reflectance spectra discriminate non-, weakly and strongly altered areas of the glasses, no matter the amount of lead in the samples.

Paper Details

Date Published: 19 July 2007
PDF: 12 pages
Proc. SPIE 6618, O3A: Optics for Arts, Architecture, and Archaeology, 66180Q (19 July 2007); doi: 10.1117/12.726091
Show Author Affiliations
Mady Elias, Institut des NanoSciences de Paris, Univ. Pierre et Marie Curie, CNRS (France)
Cécile Charbonneau, Ctr. de Recherche et de Restauration des Musées de France, CNRS (France)
Jean Marc Frigerio, Institut des NanoSciences de Paris, Univ. Pierre et Marie Curie, CNRS (France)

Published in SPIE Proceedings Vol. 6618:
O3A: Optics for Arts, Architecture, and Archaeology
Costas Fotakis; Luca Pezzati; Renzo Salimbeni, Editor(s)

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